The present invention relates to a technology related to systems in which a key has been installed and LSIs used for such systems.
In conventional key installation systems, in general, a raw key with a fixed value is installed in an LSI.
In a general CMOS LSI, it is difficult to install a key unique to the individual LSI. Because, key is implemented in General CMOS LSIs by hard-wired logic or ROM. So, key is not able to change. A key may be loaded from an external ROM. In this case, however, the key may be analyzed inside a system (set). Also, a person other than the key administrator, such as an LSI designer and a system (set) designer, may possibly come to know the key. In addition, it is difficult to write keys with different values by mass-production technology. Moreover, there is no way to verify whether or not the key has been installed correctly. That is, testing of internal keys is difficult.